<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>外部JavaScript</title>
</head>

<body>
  <!-- 引入外部js之后不可以在里面输入js代码，否则会被忽略 -->
  <script src="./js/my.js"> </script>
</body>

</html>